Electromagnetic relay having several rigid contacts



Nov. 24, 1964 w. DE FLIGUE 3,158,712

ELECTROMAGNETIC RELAY HAVING SEVERAL RIGID CONTACTS Filed Nov. 29, 1962 4 fm/amici' 9 Vladimir' De FII-gd@ B/M MMSM United States Patent O Se, a7 4 Claims. (Cl. 20th-87) ln rigid contact type relays having more than one operative contact in at least one of the two directions of arma-ture movement, the contacts must be in alignment, -that is, there must be substantially simultaneous closure of all, and no-t just some, of the contacts when excitation reaches a `critical value, and the attracting or restoring force applied to the Iarmature must be d-istributed as between the various contacts. The reason Afor such alignment is that it is impossible to adjust the contact-s satisfactorily when the relay is initially adjusted; also, the contacts may wear unevenly during the life of the relay.

Alignment is usually achieved by means of ilexible strips which bear the contacts, but this system, although very common, has a number of disadvantages. The electromagnet and the restoring device must overcome the resilience of one strip for the contact of the next strip to close, but the power required to overcome this resilience is not negligible `and increases the current consumption of the relay. if the current is supplied in a progressively increasing or decreasing fashion, the relay armature may stop in an intermediate position in which one contact has been closed but the next Contact which should also have been closed has not been closed. The inherent strength of the strips in dependence upon time and temperature is inconstan-t, with detriment to the accuracy of the relays using such strips. Often, the `armature strikes either the attracting pole or appropriate stops vat the end of its movement, and so the contact pressure is equal just to the pressure of the flexible strips, and some `of the attractive force is not used to provide increased contact pressure.

lt is therefore preferred to provide `a rigid support for the contacts, more particularly in sensitive precision relays, but means are then required to align the contacts.

According to this invention, in an electromagnetic relay comprising an electromagnetioally actuated armature in the form of an elongated plate which is adapted to pivot around a transverse axis, the armature being urged .at least in one tilting direction by electromagnetic forces acting in opposite directions on either side of the said axis, the bearings for pivot pins providing the said axis are so devised that the pivot pins can ymove in a direction substantially perpendicular to the plane of the armature plate, while the armature has, to one side of the said axis and on one Surface, a first rigid contact surface and, to the other side of the axis and on the opposite surface of the plate, a pair of second rigid and adjacent Contact surfaces arranged symmetrically of a plane which is perpendicular to the axis and which passes through the rst Contact surface, the three rigid contact surfaces co-operating respectively with three stationary rigid contact elements.

The relay may comprise a C-shaped yoke, the armature being disposed between the ends of the yoke and co-operating at one end with the inside face of the corresponding end of the yoke and at its other end with the outside surface of the other end of the yoke.

The electromagnetic relay thus comprises a number of rigid contacts, contact alignment being achieved while using a reduced power in the relay winding. The invention is therefore particularly suitable for delicate pre- 3,l58,7l2 Patented Nov. 24, 1964 4ICC cision relays including those in which the armature is restored by means of a permanent magnet, that is, in which there is considerable mechanical independence as between the yoke and the armature, so that the relay has a high snap action in both directions.

Forces acting to opposite hands, on either side of the axis, upon the armature, that is, forces which produce a couple relatively to such axis, can be produced in the release directions of the relay by two restoring devices, which may be permanent magnets or springs, arranged to operate in opposite directions.

The relay can comprise a C-shaped yoke associated with two restoring devices operative to opposite hands so that the armature can be associated with three contact studs in both pivoting directions. With this arrangement, as the armature tilts, that stationary contact which is first encountered by the corresponding rigid contact on the armature acts as a bearing for the armature until further movement thereof leads to it touching, by way of a second rigid contact, a second stationary contact, whereafter the `armature in its further movement pivots around the axis defined by these two bearing points until the third con-tact encounters the corresponding stationary contact, so that the armature is engaged with three fixed contacts disposed in a triangle either by the attracting couple or by the restoring couple.

ln this operation the armature starts to move around its pivot axis, then continues its movement by its kinetic energy until the three armature-mounted contacts have engaged with the three stationary contacts, and the ends of the armature axis may move relatively to the yoke.

lf the armature-mounted contacts are insulated from each other, three diiferent electric contacts can be operated to either hand of armature movement. Inter alia, if the armature-mounted contacts are associated electrically in pairs, the invention leads to the provision of a triple change over switch.

In one simple `and advantageous form of the invention in `order that the pivot axis may move perpendicularly to the armature plane, the axis is provided by pivot pins which engage in apertures which are elongated in the required direction of movement. Assuming that the contacts are disposed symmetrically of the axis and that there are initially substantially negligible alignment errors, the amount of such elongation should correspond to half the possible contact wear if the armature co-operates with three contact elements only in one of its pivoting directions, but equal to the whole of such wear if the arma-ture tto-operates with three contact elements in each of its two tilting directions.

One form of the invention is shown in the accompanying drawings, in which:

liG. 1 is a perspective view;

FlG. 2 is a longitudinal section; and

FG. 3 is an end elevation.

The relay illustrated in the drawings is of the kind disclosed in my USA. iatent No. 3,013,136 and comprises a C-shaped yoke 1 formed by two parts abutting each other along an inclined boundary 2 and mounted inside a former 3 for a winding d which energises the relay. An armature '7, pivotable around a transverse axis 8, cooperates, with an inside surface S and an outside surface 6 of the yoke 1. ln practice, the axis S is provided by two aligned pivot pins do and 8b projecting from side edges ot the armature 7. rIhe armature 7 is urged in a return movement by a permanent magnet 9 borne by a thickened flange 3a on one end of the former 3. The other end 3b `of the former 3 bears a stationary breakcontact element it? which limits the armature return movement produced by the magnet 9; also mounted on the end 3b is a stationary make-contact element lll which limits 3 the movement of the armature 7 when the same is attracted by the yoke l.

Electricity is supplied to the armature '7 by way of a exible conductor l2 connecting the armature to a bar i3 which provides the bearing for the pivot pin da; the bearing for the pivot pin db is provided in another bar 23. The current, supplied by way a connecting part i3d at the end of the bar l, can flow either through the Contact element lil) or through the contact element il, depending upon the state of energisatio-n of the relay.

The bearings in which the pivot pins 8a and Sb can pivot taire the form of apertures 2@ which are oval with the major axis in a direction substantially perpendicular to the plane of the armature 7. Alternatively, the pivot pinsV tia, 8b can be ltted in miniature ball bearings whose outer races are borne in an oval casing in which the pivot and bearing assembly can move perpendicular to the armature '7. The armature F has a hooked end lift which surrounds the yoke arm l? which provides the inside attracting surface 5, the hooked end M being above and opposed to the magnet 9. T he outer corners of the magnet 9 are chamfered in order to concentrate the magnetic force towards the longitudinal axis of the armature 7'. The part supports, with the interposition of an insulating strip t6, a conductive strip l'' opposed to two stationary malte-contact elements lg and i9 which extend, after the fashion of gallows, above the part ltd.

The device operates as follows:

ln the normal position, that is, with the permanent magnet 9 attracting that end of the armature 7 which is on the left in FlGS. 1 and 2, the pivot pins 8a and b bear against the bottom edge of the apertures Ztl, while the opposite end of the armature 7 bears against the stationary break-contact element lil. When the winding 4 is energised, the two surfaces 5 and 6 attract the armature 7 simultaneously so that the armature tilts around its axis 3. Since the attraction provided1 by the surfaces 5 and 6 is substantially equivalent to a couple, the thrust reaction applied to the axis tl is negligible. The right-hand end, FlGS. 1 and 2, of the armature 7 moves towards the make-contact element il, while the strip ll at the lefthand end of the armature .7 moves towards the two make- Contact elements i8 and i9.

If all the stationary contact elements lll, l, :i9 are correctly adjusted, armatur 7 engages with all of them simultaneously and without any movement of the axis 8. lf, however, the armature touches, for instance, the contact element il first, any further movement of the armature 7 shifts the two pivot pins 8a and Sb upwards in the apertures Ztl until the armature engages with the stationary contact elements i8 and 19. lf the levels of the elements le and l are slightly different from one another, the armature "7 pivots around the axis defined by the element lll and whichever of the elements i8 and 19 it touches first, until contact is made with all three elements ll, i8, i9. Clearly, the armature can perform these various pivoting movements because, the contacts i8 and l@ being close together and in an alignment which is parallel to the pivot 8, the armature can pivot, for instance, around the axis provided by the elements lll and 118, which latter axis is substantially perpendicular to the axis S, without any risk of the pivot pins do and Sb jamming in the oval apertures Also, tilting of the armature is facilitated by the restoring force of the magnet 9 being localised towards the longitudinal axis of the armature.

in make position the armature rests on the three contact elements il, l, t9 disposed in a triangle, while the pivot pins and S11 bear laterally against the long edges ofthe apertures Ztl.

ln practice, the contact elements lll, 1d, l@ are so adjusted in height that, assuming that the armature is infinitely thin, the elements lll, lig, il@ bound a plane disposed very slightly above the bottom edges of the two apertures 2i?, Consequently, because of the snap action of the armature produced by the magnetic attraction of the yoke ll, and by the permanent magnet 9, the three contacts il, litt, i9 close substantially simultaneously, or at any rate it is impossible for a contact to stay open while the other two are closed. The snap action and the localisation of the magnetic forces are adequate to overcome bearing friction. Also, the kinetic energy of closure of the contact l1 is partly dissipated in the translational movement of the pivot pins and 8b, thus reducing rebound from the Contact lill.

if a return device, operative on the armature 7 in the opposite direction to that in which the magnet 9 is operative, and with a comparable force, is provided at the end near the contacts l0 and il, for instance, by a permanent magnet being placed above that part of the armature which coaoperates with the contacts l@ and il, a second pair of contacts which are symmetrical of the contacts lil and i9 in relation to the plane of the armature 7 can be associated with the contact liti, so that three contacts are made during the return movement of the armature.

When, as is the case illustrated in the drawincs, the armature touches three Contact elements only in one direction of pivoting, the ditference between the length of the major axis of the oval apertures 2b and the diameter of normal circular bearing apertures for the pivot pins 8u and 8b need correspond to only half of the maximum possible contact wear, assuming that the initial adjustment for incorrect alignment is negligible, but if, referring to FlG. 2, it is assumed that a pair of contact elements associated with the element lli are placed opposite the elements t8 and i9 on the other side of the armature, the armature eifecting a movement equal to the distance between the elements l0 and l1, the said difference of the apertures Ztl must be equal to the whole of the possible contact wear if the pivots 8a and 8b are never to bear against the ends of the oval apertures 2?.

In the embodiment illustrated, the armature operates as a changeover device between the contact elements lt! and lll, and as an on-oif switch between the contact elements 13 and ll9.

The strip 17 can be replaced by two separate contacts insulated from one another and connected externally by flexible conductors similar to the conductor l2. Where three stationary Contact elements are used in each direction of pivoting, such contact elements can, in pairs, be changeover Contact elements similar to the elements 10 and lll.

The position of `the stationary Contact elements can be adjusted in any appropriate manner but is preferably adjusted in the manner disclosed by my aforesaid US. patent that is, by means of two screws 2d which have frustumshaped heads and which are parallel and in contact with one another and which are engaged in an elongated aperture in the support for the stationary contact elements.

Of course, the embodiments hereinbefore described can be modified, inter alia by the substitution of equivalent technical means, without for that reason departing from the scope of this invention.

What I claim and desire to secure by Letters Patent is:

l. In an electromagnetic relay comprising an elongated fiat armature having two ends and two surfaces, pivoting means for supporting said armature around a substantially medial transverse axis, means providing electromagnetic forces for tilting said armature about said axis in one direction and means for providing restoring forces for tilting said armature about said axis in the reverse direction, at least one of said means for providing forces acting on both said ends of said armature, means for restricting the displacements of said armature when said armature is tilted, a first rigid contact surface carried by one of said ends of said armature on one of said surfaces thereof, two adjacent rigid contact surfaces carried by the other of said ends of said armature on the other of said surfaces thereof, said two adjacent contacts being symmetrically disposed with respect to a plane which is per- E pendicular to said axis and said first rigid contact surface being disposed so that the aforementioned perpendicular plane passes through said first contact surface, and three stationary rigid contact members respectively cooperating with said first and two adjacent contact surfaces.

2. An electromagnetic relay comprising a fiat elongated frame, a pair of connecting bars disposed on either side of said elongated frame and having .two coaxial apertures elongated in a direction substantially perpendicular to said frame, an elongated fiat armature having first and second surfaces and having longitudinal and transverse perpendicular and bisecting axes, pivoting means mounted on said armature and aligned along said transverse axis and engaging said apertures, a C-shaped magnetic core secured to said frame having one end facing said first surface of Said armature and the other end facing said second surface of said armature, said first surface facing toward the medial portion of said C-shaped magnetic core and said second surface facing away from the medial portion of said C-shaped magnetic core, electrical means for energizing said core for tilting said armature in one direction about said pivoting pins, restoring means for tilting said armature in a reverse direction, a first rigid contact surface mounted on one of said ends and said first surface of said armature and disposed substantially along said longitudinal axis of said armature, two adjacent contact surfaces carried by the other of said ends and said second surface of said armature and symmetrically arranged with respect to said longitudinal axis, and three stationary rigid contact members mounted on said frame respectively cooperating with said contact surfaces.

3. An electromagnetic relay as set forth in claim 2, wherein said restoring means comprises at least one permanent magnet mounted on said frame.

4. An electromagnetic relay as set forth in claim 2, said relay further comprising a second contact surface mounted on said end of said armature which carries said first contact surface and said second contact surface mounted on said second surface of said armature, and a stationary rigid contact member mounted on said frame for cooperating with said second contact surface.

References Cited in the file of this patent UNITED STATES PATENTS 2,344,809 Eaton Mar. 2]., 1944 3,013,136 De Fligue Dec. 12, 1951 3,076,073 Townsend Ian. 29, 1963 

1. IN AN ELECTROMAGNETIC RELAY COMPRISING AN ELONGATED FLAT ARMATURE HAVING TWO ENDS AND TWO SURFACES, PIVOTING MEANS FOR SUPPORTING SAID ARMATURE AROUND A SUBSTANTIALLY MEDIAL TRANSVERSE AXIS, MEANS PROVIDING ELECTROMAGNETIC FORCES FOR TILTING SAID ARMATURE ABOUT SAID AXIS IN ONE DIRECTION AND MEANS FOR PROVIDING RESTORING FORCES FOR TILTING SAID ARMATURE ABOUT SAID AXIS IN THE REVERSE DIRECTION, AT LEAST ONE OF SAID MEANS FOR PROVIDING FORCES ACTING ON BOTH SAID ENDS OF SAID ARMATURE, MEANS FOR RESTRICTING THE DISPLACEMENTS OF SAID ARMATURE WHEN SAID ARMATURE IS TILTED, A FIRST RIGID CONTACT SURFACE CARRIED BY ONE OF SAID ENDS OF SAID ARMATURE ON ONE OF SAID SURFACES THEREOF, TWO ADJACENT RIGID CONTACT SURFACES CARRIED BY THE OTHER OF SAID ENDS OF SAID ARMATURE ON THE OTHER OF SAID SURFACES THEREOF, SAID TWO ADJACENT CONTACTS BEING SYMMETRICALLY DISPOSED WITH RESPECT TO A PLANE WHICH IS PERPENDICULAR TO SAID AXIS AND SAID FIRST RIGID CONTACT SURFACE BEING DISPOSED SO THAT THE AFOREMENTIONED PERPENDICULAR PLANE PASSES THROUGH SAID FIRST CONTACT SURFACE, AND THREE STATIONARY RIGID CONTACT MEMBERS RESPECTIVELY COOPERATING WITH SAID FIRST AND TWO ADJACENT CONTACT SURFACES. 